A distributed antenna system (“DAS”) can include one or more head-end units and multiple remote units coupled to each head-end unit. A DAS can be used to extend wireless coverage in an area. Head-end units can be connected to base stations. A head-end unit can receive downlink signals from the base station and distribute downlink signals in analog or digital format to one or more remote units. The remote units can transmit the downlink signals to user equipment devices within coverage areas serviced by the remote units. In the uplink direction, signals from user equipment devices may be received by the remote units. The remote units can transmit the uplink signals received from user equipment devices to a head-end unit. The head-end unit can transmit uplink signals to the serving base stations.
In a simulcast mode, each downlink cell signal associated with a base station can be distributed across multiple DAS remote units such that multiple DAS remote units radiate the same downlink cell signal. It can be difficult in the simulcast mode to determine neighboring relationships down to each remote unit between cells inside the DAS and cells outside the DAS. An internal cell can refer to a cell associated with a base station connected to the DAS. An external cell can refer to any other cell associated with base stations not connected to the DAS, which can include cells belonging to a cellular communications network. In a scenario in which a DAS is located, for example, in a building, the radio footprint of external cells may overlap with the radio footprint of the internal cells associated with the remote units inside the building. Using the same cell ID for both an internal cell and an external cell can create a cell ID conflict which can degrade the overall network performance.